U.S. Pat. Nos. 3,406,704 and 3,626,964 both disclose a magnetic valve for regulating the flow of magnetic particles. As generally shown, these valves include an outer housing and a core assembly disposed within the outer housing to define an annular flow passage. The core assembly houses a magnet/coil assembly. The magnet/coil assembly includes a permanent magnet positioned between two pole pieces and an electromagnetic coil wound about the permanent magnet. The permanent magnet provides a constant magnetic field which is transmitted through the pole pieces to block the flow of magnetic particles through the flow passage. When a current is induced in the electromagnetic coils, a counter-acting magnetic field is created to cancel the influence of the permanent magnet. This allows free particle movement through the flow passage. Varying the current induced in the coil controls the generated field and the corresponding rate of particle flow through the passage. Consequently, the valve can regulate the flow rate between an open free flow condition whereby the magnetic field of the coil completely cancels the magnetic field of the permanent magnet and a closed fully retarded flow condition with no counter-acting magnetic field influencing the strong magnetic flux of the permanent magnet.